Pump power calculator
Pump power is flow times head times density times gravity, divided by however efficient the pump and motor are.
L/s
kg/m3
%
%
per kWh
Electrical power drawn
3891.5W
- Hydraulic power delivered
- 2451.7
- Shaft power
- 3502.4
- Shaft power in horsepower
- 4.697
- Overall efficiency
- 63.00 %
- Annual energy
- 7783 kWh
- Annual running cost
- 1556.61
Show the working
- Flow rate = 10
- Total head = 25
- Fluid density = 1000
- Pump efficiency = 70
- Motor efficiency = 90
- Hours a year = 2000
- Electricity price = 0.2
- flow_m3s = 10 / 1000 = 0.01
- Hydraulic power delivered = 0.01 * 25 * 1000 * g0 = 2451.66
- Shaft power = 2451.66 / (70/100) = 3502.38
- Electrical power drawn = 3502.38 / (90/100) = 3891.53
- Shaft power in horsepower = 3502.38 / 745.69987158227022 = 4.696 76
- Annual energy = 3891.53 / 1000 * 2000 = 7783.06
- Annual running cost = 7783.06 * 0.2 = 1556.61
- Overall efficiency = 3891.53 > 0 ? 2451.66/3891.53*100 : 0 = 63
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- hydraulic power = rho g Q H
- electrical power = hydraulic / (pump efficiency x motor efficiency)
Pumps often run far from their best efficiency point. A pump throttled by a valve is wasting most of the difference.